11 January 2006 Case of the Week #33
These cases can also be accessed by clicking on the Case of the Week button on the left hand side of our Home Page at www.PathologyOutlines.com. This email is sent only to those who subscribe in writing or by email. To view the images or references, you must click on the links in blue.
To subscribe or unsubscribe, email info@PathologyOutlines.com, indicating subscribe or unsubscribe to Case of the Week. We do not sell, share or use your email address for any other purpose. We also maintain two other email lists: to receive a biweekly update of new jobs added to our Jobs page, and to receive a monthly update of changes made to the website. You must subscribe or unsubscribe separately to these email lists.
We thank Dr. Michael Constantinescu, Armstrong County Memorial Hospital, Kittanning, Pennsylvania (USA) for contributing this case. We invite you to contribute a Case of the Week by sending an email to
NPernick@PathologyOutlines.com with microscopic images (any size, we will shrink if necessary) in JPG or GIF format, a short clinical history, your diagnosis and any other images (gross, immunostains, EM, etc.) that you have and that may be helpful or interesting. We will write the discussion (unless you want to), list you as the contributor, and send you a check for $35 (US) for your time after we send out the case. Please only send cases with a definitive diagnosis.
Case of the Week #33
A 48 year old man with GI symptoms was discovered to have a 4 cm stomach tumor.
Micro images (low to high power): image #1; #2; #3
Immunostains: CD117-low power; CD117-high power
What is your diagnosis?
(scroll down to continue)
Gastrointestinal stromal tumor (GIST) of stomach
In 1983, Mazur and Clark suggested that GIST tumors, once thought to be derived from smooth muscle, might have a neural origin (AJSP 1983;7:507). Subsequent work has demonstrated that these tumors differentiate along the lines of the interstitial cell of Cajal, involved in the gut pacemarker activity that regulates peristalsis.
Two thirds of all GIST tumors arise in the stomach, where their behavior is usually benign. In the stomach, poor prognostic factors are location in the fundus or GE junction, coagulative necrosis, ulceration and mucosal invasion (AJSP 2005;29:52). Morphology for tumors from various sites has also been used to predict behavior, with pure or mixed cellular spindle cell or epithelioid cell patterns associated with benign behavior and other patterns considered not to be benign (AJSP 2002;26:705)
These tumors are immunoreactive for CD117 / KIT (Hum Path 2002;33:669), as well as CD34. Of note, the interstitial cell of Cajal is also CD117+ and CD34+.
A novel therapy for metastatic or unresectable CD117+ GIST tumors, as well as CML and other CD117+ tumors, is STI-571 (Gleevec, imatinib mesylate), an inhibitor of receptor tyrosine kinase. It inhibits constitutive activation of mutated KIT, and confirmation of KIT immunoexpression is required for its use (Pathol Int 2006;56:1). In the present case, with no evidence of metastatic tumor, treatment consisted only of tumor excision.
Additional references: Mod Path 2003;16:366
30100 Telegraph Road, Suite 404
Bingham Farms, Michigan (USA) 48025